Priming system for centrifugal pumps



"Nimh 41o, 1942. F. s. BROADHURST 2,275,502

PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Filed Dec. 6, 1959 5" Sheets-Sheet1 March 10, 1942. F, s BRQADHURST 2,275,502

PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Filed Deo. 6, 1939 5 Sheets-Sheet 3WIr/V555.'

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MarchlO, 19.42. F. s. BRoADHURsT PRIMING SYSTEM FOR CENTRIFUGAL PUMPS Y5 Sheets-Sheet 4 Filed Dec. 6, 1939 Mmh 1o, 1942.

F. s. BRoADHuRsT PRIMING SYSTEM FOR CENTRIF'UGAL PUMPS A Filed Dec. 6,1939 5 Sheets-Sheet 5 y ra wir.;

Patented Mar. 10, 1942 UNITED .STATES PATENT OFFICE Frank S'.Broadhurst, Watertown, Mass., assgnor to De Laval Steam '.,lurbineCompany, Trenton, N. J., a corporation of New Jersey ApplicationDecember 6, 1939, Serial No. 307,743

(Cl. M13- 113) 9 Claims.

This invention relates to priming systems for centrifugal pumps.

In cases where there is no, supply of liquid available to prime, acentrifugal pump by gravity flow, or where it is undesirable orimpossible to prime the pump by the use of an auxiliary water pump, ithas been customary to provide the centrifugal pump with an air pump inthe same casing to evacuate the main pump andso render it self-priming.-A system of this character is usually unsatisfactory for severalreasons, among which may be mentioned the fact that most centrifugalpumps may not be driven for an appreciable time without priming withoutresulting` damage to their labyrinth packing, the fact that there isabsorptionof considerable power by the air pump which is runningthroughout operation of the main pump, and the fact that scoring andplugging of the air pump may occur due to grit, dirt, seaweed, etc., inthe water being pumped, some of which is passed through the air pump forsealing purposes.

It has also been customary to prime centrifugal pumps on the deliveryside, sometimes with the provision o'ffloat valves or the like designedto prevent the passage `of liquid to a vacuum pump after the centrifugal.pump is primedand' operating. The valves under such conditions areexposed to high pressures and are liable to damage by impact andplugging by solid or semi-solid material jammed against them, forexample, in the handling of sewage.

" having as their ends the proper rapid, reliable In general pumping,and particularly in the pumping of driven wells, air is carried into thecentrifugal pump with the liquid. This air is separated by thecentrifugal action of the pump and accumulates adjacent the shaft. Whenthe accumulation reaches such extent as to substantially cut off theintake passages, the pump will lose its prime, and, with previouspriming systems, it was necessary to shut down the pump, reprime, andthen restart the pumping operations. In my Patent No. 2,144,613, thereare disclosed priming arrangements for centrifugal pumps which overcomethe aforementioned objections to prior priming arrangements.

The present invention relates to priming systems of this general type inwhich priming is effected by evacuation of the suction side of acentrifugal pump, and relates more particularly to improvements on thepriming systems disclosed in my application Serial No. 260,469, filedMarch 8, 1939. .'IheV present invention involves, for example, variousimprovements whereby the operation of the vacuum pumps may be reduced toa minimum, normal operation, eventhough it involves a considerableaccumulation of gas, being accompanied with no operation of the vacuumpump or pumps unless abnormally high quantities of gas enter the system.Under normal conditions, the evacuation only takes place in the initialpriming of the system on starting. Thereafter, accumulated gas isremoved automatically by the action of the centrifugal pump itself.

subsidiary to the broad objects of the-invention just indicated arevarious secondary objects operation of the priming systems to take careof modern centrifugal pumping operations which are designed to operateautomatically over long periods with little or no attention. Specically,the subsidiary objects of the invention relate to the provision ofarrangements for taking care-of abnormal gas accumulation, for handlingwater carrying sediment or floating material, for maintaining properoperation despite surges attending unusual conditions in the supply ordischarge lines, for securing rapid and positive operation of valves,and for the priming of centrifugal pumps used in marine installations inwhich the splashing of water in priming chambers in heavy seas would belikely to disturb the operation of the priming system. Additionally,provision is made for the operation of pumps in parallel or theoperation of pumps receiving their liquid from different supplies.

The primary andA specific objects of the invention will be clear fromthe following description, read in conjunction with the accompanyingdrawings in which:

Figure 1 illustrates diagrammatically an embodiment of the inventionapplied tothe priming of a plurality of centrifugal pumps andspecifically pumps used in a marine installation;

Figure 2 is a vertical section illustrating the elements associated withone of the priming chambers of Figure 1;

Figure 3' is a similar vertical section taken at right angles to thesection of Figure 2;

Figure 4 is a wiring diagram adapted to installations of the generaltype illustrated in Figure l, but showing electrical rather than vacuumcontrol of an evacuating pump;

Figure 5 is a diagrammatic view illustrating a modification of theinvention particularly applicable to the pumping of liquid containingrelatively large quantities of gas or dirt;

Figure 6 is a wiring diagram of the installation of Figure 5;

Figure 7 is an elevationillustrating a vertical ning to the vacuum tank38. with this vacuum tank are vacuumswltches 40V pumpingarrangementapplicable particularly to marine use;

Figure 8 is a partial vertical section through the pump of the unit ofFigure 7;

Figure 9 is a view somewhat similar to Figure '7, but showing a`modified arrangement suitable for marineuse;

Figure 10 is a fragmentary vertical section through the upperportion ofthe priming chamber of Figure 9; and

Figure 11 is a Wiring diagram of the installation of Figure 9.

effective to start the motors 44 and 46 at a vac- Referring first to themodification of Figures 1, -2 and- 3, there is illustrated therein apriming system designed for marine service, though it will be readilyunderstood that it is applicable to land service as well. Brieflystated, it involves a censpectively, by motors 3 and 3', are providedwith connections 4 to their sources of supply and are adapted todischarge through the usual discharge check valves, not illustrated.Each of these pumps comprises a rotor 6 provided with the impellerpassages and receiving liquid from suction bells 8 and discharging theliquid through the discharge volute I0. If the pumps are of doublesuction type, as illustrated, a pair of suction bells arelocated at eachend ofl the rotor. It will be obvious, however, that the invention isapplicable to a single suction pump4 and to multiple.stage centrifugalpumps as well as the type illustrated. K

Located above the pumps are priming chambers I2 and I2', respectively,the arrangements of` While any 4number of pumps may be.

dicated at 2 and 2'. These pumps driven, re-

which are shown more particularly in Figures 2 and 3. Chamber I2 issupported on the pump by means of pipes I4 communicating with thechambers through openings I5 and with the upper portions of the suctionbells 8. Extending through the pipes I4 are smaller pipes I1, which openwithin the suction bells closely adjacent the shaft. These tubes areconveniently mounted by being upset at their upper ends so as to be hung`from a baille plate I6 having a central opening I8 and, except for suchopening, substantially closing the chamber I2. Above the baiileplate I6is a second baille plate 20 provided with a skirt portion 22 approachingthe plate I6 and having y openings 24 outside the skirt to furnishcommunication with the uppermost portion of the chamber I2 beneath itscover into which is tapped a .nipple 26 communicating with a valve v28controlled by a solenoid 30. Beneath the bame plate I6 the pipes I1 areslotted as indicated at I3. As will be pointed out, the high water levelis at the level of these slots, `and by reason of the presence of thebailles, water is prevented from splashing out through the outlet 26despite rolling and pitching of the ship.

In the line running from the chamber I2 above the valve 28 are, inorder, a check valve 3 2 and a stop valve 33. Similar valves, indicatedwith these numerals primed, are indicated as associated with the primingchamber. I2'. From the valves 33 and 33', respectively, extend the pipes34and 34', connected to a common pipe 36, run- Communicating uum of 18inches of mercury and to stop these motors at 26 inches of mercury,while the other may' start the motors at a vacuum of 16 inches and stopthem at 26 inches. Thus the former will normally be the controllingswitch, while the latter serves to effectits control only underemergency conditions. Both of these should be of a snap type to avoidany instability of operation. The motors 44 and 46 driving the vacuumpumps 48 and 50, respectively, areprovided in duplicate for safetypurposes. The vacuum pumps 48 and 58 are connected with the tank 38through the lines 52 and 54 with the interposition of diaphragmcontrolled check valves 56 and 58 connected through a common balancingconnection 60 to the tank 38. Such valves are of conventional type,insuring that the slightest increase of pressure in the lines 52 and 54will result in a differential action on the diaphragm positively closingcommunication' to the tank 38. Thus the vacuum in the tank is maintainedfrom the instant the motors 44 and 46 cease operating.

In the event that the pumps 48 and 50 are of the type not designed tohandle liquid except, for example, for sealing purposes, it is necessarythat any flow of liquid to them should be prevented. Accordingly, notonly is the flow of liquid to the tank 38 carefully prevented, butprovision is made to remove from the tank 38 from time to time suchliquid as may condense therein from the air. A drain pipe 62 isaccordingly connected to a three-way valve 64 which, in turn,communicates with a chamber 66 provided with a sight glass 61 andadapted to drain through a check valve 68. By turning the three-wayvalve 64, liquid may be permitted to flow into the chamber 66 While thevacuum is held in 38, the check 68 then being closed. Moving the valveto another position opens the chamber 66 to the atmosphere s'o that theliquid may flow therefrom through the check valve 68. The sight glass 61permits note to be made of the amount of water which has collected inthe chamber 38 and thus serves to advise an operator of any abnormalaccumulations of liquid.

Extending into the priming chamber I2 are lower and upper electrodes 18and 12, respectively, which electrodes function as will be bestunderstood from a modied arrangement illusy trated in Figure 4 whichwould be vapplicable if the vacuum pumps were controlled not by thevacuum in a tank such as 38, but by the liquid level in a primingchamber. l

Passing for the moment the electrical considerations, it may be statedthat the arrangement of Figures l, 2 and 3 operates as follows:

When the pumps 2 and 2' are stationary, they may be empty, and throughdisuse ak substantial pressure may exist in the vacuum tank 38.

tank 38, the liquid to be pumpedwill rise into the.

pumps -2 and 2' and through the pipes I4 and I1- into the chambers I2,and I2',V iirst submerging the lower electrodes without any actionstaking place, and iinally reaching the electrodes 12. As soon as anelectrode 12 is submerged, its corresponding solenoid 30 will bedeenergized, and its valve will close, preventing any further withdrawalof air from its priming chamber. Thereafter, air will be pumped out ofchamber 38 until the vacuum'pumps are shutl down by the action of one or`the other of the switches 40 or 42. Normally, this vacuum will bemaintained over very long periods, since, except for leakage. the pumpswill maintain their prime during operation.

When the valves 28 and 28 close, the pumps and chambers I2 are isolatedfrom each other and from the tank 38. As soon as the electrode 12 issubmerged, the corresponding pump driving motor is either automaticallystarted, or its circuit is put into condition to be manually closed. Asthe pump operates, a high velocity of ow, due to the rotation of theshaft, occurs at the lower ends of the pipes I1, producing an ejectoraction creating in the pipes I1 a lower pressure than that existing inthe pipes I4 opening in the upper portions of the suction bells wherethe liquid is relatively quiet and ejector action is not occur-A ring.Accordingly, the liquid in the chamber I2 is caused to rise until it canflow through slots I8 into the pipe I1, and thereafter a recirculationcontinues to occur upwardly through pipes I4 and down through I1. Thepressure differential producing this circulation iis suiilclent to drawdownwardly through the pipe I1 any air which might ow from the upperportions of the suction bells into the chamber I2, and accordingly smallaccumulations oi air are continuously removed. If air centrifugallyseparates about the shaft, as sometimes occurs when large quantitiesenter the centrifugal pumps, the ejector action ceases, and this airwill pass upwardly through the pipes I1 into the upper portion oi' thechamber I2. By

Vthis action, however. liquid is again caused to submerge the" lower endof the pipes I1, whereby the ejector action is renewed to graduallyWithdraw through the pipes I1 the air Whichhas accumulated in chamber I2.H The air thus withdrawn by ejector'action is in the form of iinebubbles and readily passes through the pump. Thus the prime of thepump-is maintained despite relatively large accumulations of air. OnlyVii? accumulations are such as tocause the liquid level to drop belowthe lower electrode 10 will the solenoid controlled valve open andpermitsuch air to ilow to the vacuum tank 38. 'I'he valve 28 is immediatelyclosed as soon as the liquid level is restored to the level oi' theelectrode 12. l

The action of the electrodes in effecting this control will be clearfrom consideration of Figure 4V in which, in view of the somewhat moreelabrorate controls involved, the electrodes 10' and 12' correspondingto 10'and 12, respectively, are shown associated with means forcontrolling a vacuum pump operation. In this arrangement a solenoidcontrolled valve 28' is villustrated and corresponds to the valve 28,the corresponding solenoid being indicated at 30', and operative uponenergization to open the valve 28'. At 14 there is illustrated a relayof the well known Bender-Warrick induction type. 'I'his relay is througha switch 82.

when the'coil provided with an A-shaped core having a coil `84 on itscrossbar portion grounded at one end and connected at its other end tothe electrode 12 and also to the contact element 86 of the armature-18.The upper connecting element of the core is provided with a coil 18permanently connected to the alternating current power line '80 The legsof the core are adapted to attract the armature 18, which isconventionally illustrated as adapted to close a single contact at 88 byengagement with its contact portion .88 thereby connecting theelectrodes 10 and 12'-, together. When thearmature 18 is not attracted,it closes at 90 a circuit including the coil 92, which is adaptedtoclose a switch 84 in series with a manually operated switch 88 tocontrol a vacuum pump motor 88 operating a vacuum pump adapted toproduce, either with or without the interposition of a vacuum tank, avacuum in the priming chamber such as I2. Also involved in the circuitclosed at 90 is the solenoid 30' controlling the valve 28.

When the armature `16 is attracted, there is closed at I 00 a circuitincluding a coil |02 adapted to close a switch at I04, which switch willopen |02 is deenergized only after a delay by reason ofthe provision ofa dash pot II2 controlling the movements of the switch. "I'he switch |04controls the circuit of a starting relay |06, conventionally illustratedas adapted to` controlling the motor IIO op.

vacuum pump motory 98 is immediately closed.

and the valve 28 is open. Accordingly, a vacuum is produced to causerise of liquid into a chamber such as I2. At this time, when neither ofthe electrodes 10l nor 12 is immersed in liquid, the path of themagnetic iiux Ais through the crossbar ofthe core 14 and the armature 18is not attracted. Accordingly, the coil |02 will not be energized andthe starter |08 will remain open.

When vthe liquid rises to a point to submerge electrode 10", nothingoccurs, but as soon as 12 -is submerged, a current is introduced in thesecondary coil 84 producing a ux bucking the ux tending to ilow throughthe crossbar, so that the path of the flux must now be through thearmature which is attracted opening the circuit at 90 and closing thecircuit atv |00 and connecting the electrode 10' to the electrode 412 bymaking contact at 88. As soon as the contact at is broken, the valve 28'closes, and the vacuum pump motor 96 is stopped. The coil |02 is nowenergized and serves either to operate thefstarter conventionallyillustrated at |08, or close a switch naking it possible to start themotor IIO manu- E 1y.

If the liquid level`now drops below the level 10', the secondary circuitof the relay is opened and contact at made to eil'ect opening of'thevalve'28' and renewed operation of the motor 98. The `motor IIO,however, is not immediately stopped by reason o1' the time delay actionafforded by the dash pot II2. Preferably a delay oi', say, 30 seconds orthe like is provided, during which most centrifugal pumps may safelyoperate without damage due to overheating, even if they do not containwater. Inv this limited time, ii' merely a surge hasA occurred ratherthan something serious, such as failure of the water supply, the vacuumpump will be able to restore the VUgal pump motor.

On the other hand, if, in the limited time, the liquid level is notrestored to submerge the electrode 12', the main pump motor will stopand will only restart when the water level is properly restored or whenmanual starting occurs. Y

In Figures y and 6 there is illustrated an alternative form of theinvention, particularly designed for use in connection with drivenwells, in which sand or other sediment may be carried by the inflowingwater together with large quantities of air. In such case, it isdesirable to have a separating tank precede the centrifugal pump, and itbecomes impractical to provide a time delay arrangement, as in theprevious modification, by reason of the very considerable volume oi' airwhich must be pumped to restore an abnormally low liquid level to itsnormal height.

The inlet ||5 communicating with the well or the like from which pumpingis taking place, communicates with a chamber |01 of large capacity,provided with a baiiling arrangement, indicated at |03, for preventingas much sediment as possible from entering the intake piping |03 of thecentrifugal pump |0|, in which piping there is interposed a stop valve|05. The pump delivers water through the passage and the check valve ||3and stop valve Hd.

Provided preferably as an upper unit of the separating tank, though itmay be separate, is a vacuum tank |||6communicating through connections||8 with a motor driven vacuum pump, indicated at |20. A vacuumcontrolled diaphragm type check valve |2d is interposed in the line |I8having a controlling connection |23 with the vacuum tank. A stop valve|22 is preferably provided in the same line. In an arrangement such asthis, particularly where operation of the centrifugal pump must bemaintained despite possible failures of the electrical supply, thecentrifugal pump or pumps, since a plurality may be' connected to thesame separating chamber, may

provided with energizing coil |32 permanently connected to the powerline |44, which may be connected to the main power supply through aswitch |48. The armature |60 of this relay has one contact permanentlyconnected to the electrode |38 and the coil |52 on the cross member cfthe relay, the other end of which is grounded. When the armature |33 isattracted by the core, a contact is made at |563 serving to connect theelectrodes |36 and |33 together, as in the case of r the modification ofFigure 4.

The armature |03 has. another contact making portion |50 designed toconnect the contacts at |53 to energize the coil |32 of -the valve |30to open that valve.

For the purpose of control of the motor driving the centrifugal pump,there is provided a second relay of the same Bender-Warrick typeprovided with a core |63 and an energizing coil |32, connected to theline |44. The secondary coil is connected at one end of the electrode|33 and at its other end to ground. The armature it, of this relay is ofthe type requiring manual resetting, i. e., when once dropped it can bereset only by manual manipulation of the button |65. When this armatureis attracted by the core it is adapted to close the switch con` trollingthe circuit through the starter coil |12 controlling the' switch |14 inthe line |16 to the centrifugal pump motor. Automatic starting may bethus effected, orthe arrangement may be such as merely to place themotor circuit in condition for manual starting.

In the operation of this arrangement, assumingthe electrical supply isoperating, the valve |33 will be closed, and the vacuum pump |20operating. ,This vacuum pump may be controlled by the pressure in thetank H6 as in the l case of a modification of Figure'l, or, alternabearranged to be alternatively driven by a motor.

or motors and a gasoline or similar engine. Likewise, in such cases,provision is made for driving one or more vacuum pumps alternativelyeither by an electric motor or motors or by a gasoline or similarengine. If a plurality of vacuum pumps are provided, then they should beprovided with independent connections such as I0 to the vacuum tank H6.In such case, the valve |22 serves to isolate either of the pumps forrepair purposes or, in the event, for example, 'that only one of them isoperated by a gasoline engine in an emergency, the other may be cut outof the system.

A connection |20 is provided between the upper end of the separatingtank |01 and the 'vacuum tank H6, there being interposed in thisconnection a valve |30 controlled by a solenoid V|32 and adapted to beopened when the solenoid is energized. To permit proper operation in theevent of failure of the electrical supply, an auxiliary connection isprovided between the separating tank and the vacuum tank and iscontrolled by a stop valve |39. Also provided for emergency operation isa tank |33, connected at its upper and lower portions to the separatingchamber |01 and housing a float |35 adapted to open an air vent |31. y

Extending into the separating chamber are three electrodes indicated at|34, |36 and |38. These are electrically connected into the system, asillustrated more particularly inFigure 6.

A Bender-Warrick relay, indicated at |40, is

tively, by the rise of liquid level asdescribed in the modification ofFigure 4. At any rate, it will tend to cause rise of liquid pastelectrode |34 without effecting any result, since the relay |60 is ofthe manual resetting type, and

" then past |36 without eiecting any result until the electrode |38 issubmerged. Thereupon, the

armature |48 is attracted by the core closing the' contact at |54,thereby connecting the electrodes |36 and |38 together. At the sametime, the

' contact at |58 is broken so that the solenoid |32 releases the valve|30 to closed position. At thesame time, the vacuum pump motor may bestopped, or it may be stopped only after a predetermined vacuum isproduced in the chamber H6. Whenever desired the main pump motor ormotors may be started by moving the armature |64 into the field ofattraction ofv the core |60 which is now in attracting position byreason of submersion of the electrode |34. As the centrifugal pumpoperates a circulating effect is produced as in 'the case of themodification of Figure 1, by reason of the approach of the connection||1`Yto the shaft of the pump within its eye. Accordingly, a partialvacuum is produced in the-line ||1 tending to raise the liquid in thetank |01 to the level of the connection H1, whereupon flow of liquidfrom the tank through the connection ||1 takes place with withdrawal ofair whenever any accumulation occurs in the tank |01 to cause the liquidlevel to tend to dropv beneath the connection I|1. Preferably thisconnection opens into the tank a substantial distance above theuppermost electrode |38. Thus the pump maintains itself primed and lthelevel of the liquid in the tank.

.vent |31 to the atmospher an installation of this character I tinuouslyoperated and' is indicated at |88 asv Under these conditions, no liquidenters the float chamber |33.

In the event that an abnormal accumulation of air occurs, or, for someother reason, a surge occurs tending to drop the liquid level, the valve|30 will not reopen until the liquid level drops below the middleelectrode |36. When such drop occurs. however, immediately opening willtake place so that air may ow into the vacuum tank and the level will berestored. As soon as |38 is again submerged, the valve |30 will close.If the surge or accumulation of air is abnormal and the liquid clearsthe electrode |34, the core Ill will drop its armature and thecentrifugal pump motor will be stopped and can be restarted only bymanual intervention.

If for some reason the valve |30 should stick in open position, liquidmight enter the chamber ||6 and cause damage to the vacuum pump. Toavoid any possibility of the occurrence of this, the oat valve |35 isprovided which, if the liquid level rises abnormally, will open the sothat air will 110W through this vent into the upper portion of tank |01and -then into the vacuum tank, preventing any liquid from risingtherein and at worst merely producing an abnormal continued operation ofthe pump |20.

The float valve |35 has another emergency function coming into play whenthe electrical supply fails. Under such conditions, the valve |30 wouldremain closed, since all of the electrical parts of the installationwill be ineffective. To permit operation in such case, the valve |39inthe bypass is ope'n and both the centrifugal pump and vacuum pump are'operated by the emergency engines. The float valve |35 will Vnowprevent, 4as before, any rise of liquid above the level tending tounseat its valve member from the vent |31.` Any accumulated air is drawnoff through the valve |39. Continuous operation of the vacuum pump must,of course, take place.

In Figures 7 and 8 there is shown an alternative arrangement involving acentrifugal pump with its axis vertical particularly adapted for marineinstallations. In this case, the pump, indicated at |80, is driven bythe motor |18, and its suction bell, in this case arranged uppermost,takes liquid through the intake connection 82, the liquid beingdischarged from the pump through the outlet connection |84 inwhich isinterposed in conventional fashion a combination check and stop valve|86. The Avacuum pump in may be condriven continuously by the motor |18.It is connected through the passage |90, in which is interposed thevalve |94 controlled by the solenoid |98, to the upper end of astandpipe |98. The lower end of this lstandpipe at 200 communicates witha pipe 20| which, at 2,02, is connected into the intake passage |82.`Electrodes 204 and 206 are located as indicated in the standpipe |98 andcorrespond to the electrodes 10 and 12' of Figure 4, with the exception,however, that they control only the valve'l94 corresponding to 28 ofFigure 4, and have no control over the motor |18. Above the'electrode206 the standpipe |98 is connected through pipe 208 to the tube 2|0passinginto the suction bell of the pump and extending closely adjacentits shaft 2 |2.

The centrifugal pump in this case must be of a type which can runfor'extended periods in dry condition.` Since high efficiency is notparticu-- ing, which, when the By reason of the ejector 5 larlynecessary in pumps for marine installations, the runner clearances maybe larger than in the `case of land pumps, and the pumps may runindefinitely while dry without damage. If closer clearances are present,however, it may be desirable to lead from the water line `2|4|` whichnormally supplies water through 2 I6 to the packing gland of the pumpsome additional ilow through pipes 2|8 and passages 222 to the wearingrings 224 'serving for their temporary coolpump is operating to pumpwater, is effected by the water being handled.

In the vacuum linethere is preferably pro- -vided a relief valve |92which will open this |18 is started and the valve |94 is open, due toVenergization of its solenoid |96. Accordingly, a vacuum is drawn fromthe standpipe and the liquid to be pumped rises in the intakeconnections and the pump and through connection 20| in the standpipe |98until the upper electrode 206 is submerged, whereupon the valve |94closes, and shortly thereafter the relief valve |92 opens. action at theend of the tube 2|0 approaching the shaft 2|2 a difference in pressureis produced as in the other modifications, causing a further rise ofliquid in the standpipe |98 and then flow of liquid therefrom throughconnection -208 to the suction chamber of the pump. Thus continuousremoval of air which may accumulate in the standpipe through the intakeconnections in the passage 20| occurs. If any abnormal amount of airaccumulates in the suction bell of the pump so that the tube 2|ll whichis in its upper portion is uncovered, the ejector-action will cease andthis air will flow yinto the upper portion of the standpipe |98.

soon as the tube2l0 is again submerged, howremoving from the standpipethe air which has owed therein. If the liquid level falls below thelevel of the electrode 204, the valve |94 will be opened and the vacuumpump will again act to draw a vacuum in the standpipe to reprime thesystem.

'I'he systems so far described are adapted for operation only withalternating current if the Bender-Warrick type of relay is to be used,since a current introduced in the secondary thereof is responsible forits operation. It may be noted that it is not generally permissible toprovide electrodes for operating purposes which are connected directlyto a'power supply, since accidental grounding might very well occur.'I'he Bender- Warrick type of relay, on the other hand, provides athoroughly safe arrangement, since the secondary is of such highresistance that even complete short eircuiting of it will not result inany abnormally high current flow. Furthermore, the voltages induced inthis secondary are suf- .ciently high to overcome the relatively greatresistances of waters matter.

While alternating current is available on -many ships, there are otherson which only direct current is available, and for proper operation ofthe priming system in such cases, there must be provided a switchingarrangement which is illustrated in the modification of .Figures 9,10and 11 in conjunction with other features of the ar-` rangement. Y

containing little mineral trolled.

In these figures there is indicated at 230 a motor arranged to drive thecentrifugal pump 232. This motor may be automatically controlled, as inthe previous modication, or manually con- A suction manifold, indicatedat 234, may .be selectively connected, for example, to various bilgesand the line running therefrom to the centrifugal pump 232 contains thecombination stop and check valve 236 of conventional type. Dischargetakes place through a similar valve indicated at 238.

Communicating with the intake connection at 240 isa standpipe 242,extending from which is the vacuum line 252 controlled by the solenoidcontrolled check valve 250. The vacuum producing-device used in thisinstance may be either automatically controlled or manually controlledwhen the pump is operated. In either case, as will be evident hereafter.the valve 250 controls automatically the priming operation.

A connection indicated at 244, similar to the connection 208 of themodification of Figure 7, furnishes communication between the upperportion of thestandpipe 242 and the suction bell of the centrifugalpump, extending therein closely adjacent the shaft.

In the present case, instead of using electrodes,

there extend into the pipe shells 246 and 248 in which are located,respectively, lower and upper floats 264 and 258. These oats control,through interposition of an expandible bellows arrangement, switches 262and 260, which should be of snap type to secure rapid'making, andbreaking of contact. Such switches are well known per se, and need notbe specifically described. Above the uppermost float 258 is anarrangement of bailles 254 and 256, designed to prevent the splashing ofwater into the vacuum connection when the arrangement is used in marineservice.

to the oat 258 and does not reopen until the liquid level drops belowoat 264, giving rise to the same general type of operation as heretoforedescribed with reference to the electrode arrangements.

As soon as the pump is primed, a suction is produced in the connection244, as in the previous4 modications, and by reason of the ejectoraction which then takes place, the liquid level is raised to the levelof the connection between pipe 244 and the standpipe 242. Airaccumulations are removed, asin the case of the previous modication.

It will be evident that the modifications specifically referred toherein as for marine use may be used in land installations, in whichcase the bafes become unnecessary. It may also be pointed out that themodification in Figures 9, 10 and 11 is applicable to alternatingcurrent operation as well as direct current operation.

It will be evident that various changes in details of the invention maybe made within the scope of the appended claims.

What I claim and desire to protect by Letters Patent is:

1. In combination, a centrifugal pump; means providing a chamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped;

means for evacuating said chamber to raise liquid therein to a levelabove the intake passage to thereby prime the pump: means connected tosaid chamberand subjected to an ejector action of liquid within theintake passage and being pumped to maintain a partial vacuum vin saidchamber, said last means comprising'a tube opening closely adjacent theshaft of said pump and subjected to the ejector action of liquidadjacent 'said shaft; an electrode within said chamber The switches 258and 264.are connected in circuit as indicated in Figure 11. A relaycoilv 210 is adapted to close contacts through armatures 212 and 214.When the latter is closed it serves to energize theA solenoid 268controlling the valve 250 to hold this valve open. The oat switches 256and 264 are arranged to open when liquid` rises to rtheir level. v

The operation of this arrangement is quite similar to that ofthe'arrangement of Figure 7. When the liquid level is below the floatswitch 264, the circuit is closed at 260 and 262 through the solenoid216, and also through the action of the relay armature 212, which, itwill be noted, is in parallel with 262. AccordinglyVV the solenoid 268is energized and the valve `25|) held open to permit the withdrawal ofair.

When in the priming operation the liquid rises to the level of the float264, switch 262 is opened, butwithout effecting any result,since thecircuit is closed in parallel with this switch at 212. When the levelrises to the float 258, the switch 260 is opened. deenergizing the coil210 and thus permitting it to drop the conductors 21.2 and 214,deenergizing the solenoid 268, whereupon valve 250 closes undertheaction of its controlling spring. l

When the liquid level drops, there will first occur closure of switch260, but this will have no effect, since the switch 262 remains open andthe conductor 212 is already in open position.

jacent said shaft; and means comprising a sole# below the top thereof;and means operating when liquid reaches said electrode to closecommunication between the chamber and'said evacuating means, whereby themeans subjected to said ejector action serves alone to maintain thepartial vacuum in said chamber. 1

2. In combination, a centrifugal pump;'means providing a chamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped; means for evacuating saidchamber to raise liqvuid therein to a level above the intake passage tothereby prime the pump; means connected to said chamber and subjected toan ejector action of liquid within the intake passage and being' pumpedto maintain a partial vacuum in said chamber, said last means comprisinga tube opening closely adjacent the shaft of said pump.

and subjected to the ejector action of liquid adnoid controlled valveeffective to close communication between the chamber and said evacuatingmeans when liquid in the chamber reaches a predetermined level below thelevel of connection with the chamber of the means subjected to saidejectoraction of liquid.

3. Incombination, a centrifugal pump; means providing a chamberconnected to` the intake passage of the centrifugal pump for accumula-As soon as the float 264, however, is uncovered, v

switch 262 closes, whereupon the relay 216 is energized and the valve250. is opened. T'hus` the valve 250 does not close until the liquidlevel rises tion of gas contained in theliquid being pumped; meansconnected to said chamber for evacuating it to raise liquid therein to alevel above the intake passage to thereby prime the pump; meansconnected to said chamber and subjected to an ejector actio'n,of4liquidwithin the intake passage and being pumped to maintain a partial vacuummeans to prevent splashing of liquid to thelast' Vnamed point ofconnection.

4. In combination, a centrifugal pump; means providing a chamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped; means connected to saidchamber for evacuating it to raise liquid therein to a level above theintake passage to thereby prime the pump; means connected vto saidchamber and subjected to an ejector action of liquid Within the intakepassage and being pumped to maintain a partial vacuum in said chamber,said last means comprising a tube opening closely adjacent the shaft ofsaid pump and subjected to the ejector action of liquid adjacent saidshaft; and means eiIective to close communication between the chamberand said evacuating means when liquid in the chamber reaches apredetermined level below the level of connection with the chamber ofthe means subjected to said ejector action `of liquid; and baiies withinthe chamber located above the level of connection with the chamber ofthe means subjected to said ejector action of liquid and below theconnection with the chamber of' said evacuating meanstoprevent splashingof` liquid to the last named point of connection.

5. In combination, a centrifugal pump; means providing a chamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped; means connected to theupper portion of said chamber for evacuating said chamber to raise`liquid therein to a level above the intake passage to thereby prime thepump; means for limiting the average level to which liquid will rise insaid chamber during operation of the pump; and baille means locatedabove said average level and below the level of connection with thechamber of the means for evacuating said chamber to prevent splashing ofliquid to the last named level.

6. In combination, a centrifugal pump; means providing a chamberconnected Vto the intake passage of the centrifugal pump for accumula.,

tion of gas contained in the liquid beingV pumped;

means for evacuating said chamber to raise liquid and subjected to theejector action of liquid adjacent said shaft; and electricallycontrolled means effective to close communication between the chamberand said evacuating means when liquid in the chamber reaches apredetermined level below the level of connection with the chamber ofthemeans subjected to said ejector action of liquid. l

7. Incombination, a centrifugal pump; means providing a Achamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped; means for evacuating saidchamber to raise liquid therein to a level above the intake passage tothereby prime the pump; means limiting the level to which liquid mayrise in said chamber under the action of said evacuating means; andmeans effective following a predetermined delay after the liquid level`drops to a predetermined level lower than the aforementioned level tostop the operation of said centrifugal pump.

8. In combination, a plurality of centrifugal pumps; means providing aplurality of chambers, one for each pump, connected to the intakepassages of the centrifugal pumps for accumulation of gas contained inthe liquid being pumped; common means for evacuating all of saidchambers to raise liquid in each to a level above the intake passage ofthe corresponding pump to thereby prime the pump; means connected toeach chamber and subjected to an ejector action of `liquid within itsown intake passage and being pumped to maintain a partial vacuum in eachchamber; and means individual to the chambers effective to closecommunication between any chamber and said evacuating means when liquidin said chamber reaches a predetermined level below the level ofconnection with said chamber of its means subjected to said ejectoraction of liquid.

9. In combination, a centrifugal pump; means providing a chamberconnected to the intake passage of the centrifugal pump for accumulationof gas contained in the liquid being pumped; means connected to saidchamber for evacuating it to raise liquid therein to a level above theintake passage thereby to prime the pump; means connected to saidchamber and subjected to an ejector action of liquid within the intakepassage and being pumped tomaintain a partial vacuum therein to a levelabove the intake passage to thereby prime the pump; means connected tosaid chamber and subjected to an ejector action of liquid Within theintake passage and being pumped to maintain a partial vacuum in said'chamber, said last means comprisingt a tube openingv closely adjacentthe shaft of said pump connection with the chamber of the rst mentionedevacuating means, said last means comprising a tube opening closelyadjacent the shaft of said pump'and subjected to the ejector action ofliquid adjacent said shaft; and electrically controlled means effectiveto close communication between the chamber` and the first mentionedevacuating means when liquid in the chamber reaches a predeterminedlevel below the level of connection with the chamber of the ilrstmentioned evacuating means.

FRANK s. BROADHURST.

